Output capacitor-less low dropout linear regulator (LDO) circuit has become the first choice for power management in mobile electronic devices due to its advantages of simple structure, low cost, low noise, low power consumption, small package size and the like. Because it can omit the external capacitor and the bonding gold wire at the output, the cost of the product can be effectively reduced, and then the output capacitor-less low dropout linear regulator circuit is gradually applied in SOC products.
The output capacitor-less low dropout linear regulator circuit is formed mainly by the following parts: a voltage reference source, an error amplifier, a power transmission device, and a feedback circuit. The error amplifier compares the feedback voltage of the feedback circuit with the reference voltage of the voltage reference source, and amplifies the difference therebetween to control the conduction state of the power transmission device to obtain a stable output voltage. However, in the process of just power on, the loop just started to work, and then the error amplifier cannot effectively control operation of the power transmission device, so there will be a conduction stage for the power transmission device, which will cause the input voltage to be directly output to the output voltage terminal, resulting in the voltage overshoot. Because the parasitic capacitance of the output voltage terminal is comparatively small, the voltage overshoot will have a greater impact on the voltage of the output voltage terminal.